Electric heater for oil wells



Oct. 10, 1950 J'.- s'cHMER ELECTRIC HEATER FOR OIL WELLS Filed March 29,1948 INVENTOR.

JA/(U5 5CH/WE? ATTOQ/VEKS Patented Oct. 10, 1950 ELECTRIC HEATER FOR OILWELLS Jaknb Schlner, New York. N. Y., assigner of oneyhalf to .lackGould, New York, N. Y.

Application March 29, 1948, Serial No. 17,664

1 This invention relates to methods and means for recovering petroleumoil from the subsurface and more particularly toy methods and meansforincreasing the iiow of petroleum oil from subsurface strata -by theapplication of electrically generated heatto the oil bearing strata. Theilow of oil in the borehole diminishes graduallyduring exploitation dueto such causes as the natural impoverishment of the strata, loss ofpressure and plugging of the pores of the oil-bearing rock by depositsof paraflin Wax and/or asphaltic matter. Where highly wateremulsied oilsare not encountered, the temperature cf the oil body may be raisedsufficiently to remove the deposits of paraffin wax and/or asphalticmaterial with the use of the burner described in applicants copendingapplication entitled Methods and Means for Raising the Temperature ofOil in Oil Wells, led February 11, 1948, Serial No. 8,368, nowabandoned. In the case of highly water-emulsiiicd oils, electrical meansfor heating the cil body may be superior to the aforementioned burner.Howe ever, electrical heaters so far developed have the form of acylinder of a diameter not larger than the diameter of the casingthrough which they are introduced thereby providing a relatively smallheating surface in the center of the borehole. Thus, the heat transferfrom the heater to the walls of the borehole is hampered by the distancefrom the heater to the walls.

t is an object of this invention to facilitate the ilow and increase theoutput of oil from the well by decreasing the viscosity of the oil andby dissolving and/or melting the deposits of the wax and asphalticmatter by the application o-f electrically generated heat at or near thebottom of the borehole.

Another object of this invention is to utilize one or more electricheaters which can be lowered into r removed from the borehole throughvthe relatively narrow wall casing and which c-an be spread fan-like inthe borehole thus permitting a wider and faster distribution of heattherein.

A further object is to apply continuously or at intervals the properamount of heat in the borehole of the oil well in a most economicalmanner.

Other objects of the instant invention will become apparent in thecourse of the following specification.

In the accomplishment of these objectives, the electrical heatercomprises a cylindrical head of suitable diameter to be passed by anysuitable means through the oil well casing. Hinged to the base of thecylindrical head are a number 11 claims. (o1. 21e-e3) of longcylindrical or flat heating elements which can be spread fanewise whilein the borehole thereby permitting an easier and faster heat transfer tothe oil and to the walls of the borehole over known methods. Electricalresistance wires are wound on a porcelain core or are imbedded in alayer of asbestos or mica and are covered by sheet iron or stainlesssteel to form cylindrical or dat heating elements and are connectedthrough the cylindrical head to a suitable outside source of electricalenergy. Mechanisrn for spreading either the cylindrical or flat heatingelements in the borehole from the top of the oil well is provided. Toprevent premature spreading of the heating elements, a ring is slidablydisposed along the heating elements and adapted to be operated from thetop of the well. The electrical heating elements may be from two tofteen feet in length or even longer and the heaters may be usedindividually or in groups in accordance with the requirements.

The invention will appear more clearly from the following detaileddescription when taken in connection with the accompanying drawingshowing by way of example preferred embodiments of the inventive idea.

In the drawing:

Figures 1, 2, and 3 show one embodiment of the electrical heater forraising the temperature of the oil body in a borehole of an oil well inwhich Figure 1 is a diagrammatic View of an oil well with an electricalheater having cylindrical heating elements submerged below the level ofthe oil and constructed in accordance with the principles of thisinvention; Figure 2 is an elevational View of the electrical heatershown in Figure l, enlarged; and Figure 3 a plan View of the base of theelectrical heater shown in Figure 2.

Figures 4, 5, and 6 show another embodiment of the electrical heaterutilizing ilat electrical heating elements rather than the cylindricalelements shown in the rst embodiment and in which Figure 4 is anelevational View of the electrical heater prior to the spreading of theiiat heating elements; Figure 5 is a sectional view along the line 5 5of Figure 4 with flat electrical heating elements spread and shown infull; and Figure 6 is a sectional view along the line 6-6 of Figure 4,enlarged.

Referring now in greater detail to the drawings in which like referencenumerals indicate like parts, reference numeral l0 indicates an oilWell, il the surface of the oil in the oil Well, and I2 the electrical.heater.

The electrical heater l2 comprises a short steel cylindrical head I3,about four to ten inches in diameter and adapted to pass through thecasing I5 of the oil well I. At the top of the cylindrical head I3 isthe lifting eye or hook I6 to which one end of the rope Il is attachedby any suitable means for raising and lowering the electrical heater I2in the casing I5. Substantially along the axis of the cylindrical headI3 is an opening I6 which permits a second rope I9 to actuate thesubsequently described spreaders 23. Also in the cylindrical head I3 areproperly insulated distributors for the electrical conductors 2D and 2Idesigned for parallel connection to the resistance wires I4b,subsequently described, in the electrical heating elements I4. Thecylindrical head I3 is made tight by the proper use of plastic materialsso that no oil or brine from the well can infiltrate.

On the base of the cylindrical head I3 is a bundle of elongatedcylindrical heating elements I4 hinged by any suitable means I4a aroundand within the circumference thereof to permit the bundle to passthrough the casing I5. Within the heating elements I4 are the resistancewires I4b of nichrome or other suitable alloy imbedded in a layer ofasbestos .or mica in the general form of a sheath. The resistance wiresI4b are designed to be treated by an electrical current, usually red hotbut below l800 F. while the temperature of the surface of the electricalheating elements I4 in contact with the oil is maintained from 200 F. toabout 700 F. or below the temperatures at which a thick insulatingdeposit of carbon forms from the oil. The electrical leads connectingthe resistance wires I4b to the distributor in the cylindrical head I3are insulated by a material which is a good electrical insulator andinsoluble in oil, such as Perbunan rubber, or polyvinyl chloride orThiokol plastics. In addition the aforementioned leads which may beexposed to elevated temperatures may be supplied with a thermallyresistant insulating material such as teflon or silicons plastics. Alsoon the base of the cylindrical head I3 and in the center of the bundleof heating elements I4 is a downwardly extended tubular member 22 (Fig.2) alined with the previously mentioned opening I8 in the cylindricalhead I 3 and attached to the base thereof by any suitable means. Thetubular member 22 is of sufhcient length to prevent the subsequentlydescribed spreaders 23 from being moved upwardly beyond a straightangle. Alined with the downwardly extended tubular member 22 is the apexof an inverted collapsible conical formation of spreaders 23, similar tothe spreading mechanism of an umbrella. At about the center` of eachheating element I4 is hingedly attached a thin spring-like rod orspreader 23 having a length ranging from about one-quarter to one-halfof that of the heating elements I4. IThe bases of the spreaders 23extend downwardly between the heating elements I4 and are hingedlyconnected to each other at the downwardly extended ends and to which oneend of the rope I9, previously mentioned, is attached. Thus, by pullingupwardly in the rope I9, the apex of the inverted collapsible formationof spreaders is moved upwardly toward but not beyond the end of thetubular member 22 thereby spreading the heating elements I4 outwardly inthe manner of an umbrella.

To prevent the heating elements I4 from premature spreading, the ring 24is fitted over the ends of the elements I4 as shown in Figure 2 and madeslidable therealong. One end of a rope 25 is attached to the ring 24 andextends upwardly through the casing I5 to the surface. When it isdesired to spread the electrical heating elements I4, an upward movementof the rope 25 moves the ring 24 upwardly to the top of the members asshown in Figure 1 thereby releasing the members I4 for spreading in themanner previously described. Of course, the ropes I9 and 25 could becombined in one rope shortly above the heater I2.

In the embodiment of the electrical heater shown in Figures 4, 5, and 6,the cylindrical head 26 has a diameter suitable for passing through thecasing I5 of the oil well I0, and is made airtight to prevent injury tothe subsequently described electrical conductors 2l and 28 whichbifurcate into a number of parallel electrical paths in the cylindricalhead 26 for connection to the resistance wires 33a in the flatelectrical heating elements 29, later described.

A plurality of elongated flat electrical heating elements 29 arehingedly attached 0n the base of the cylindrical head 26 adjacent one tothe other as shown in Figures 4, 5, and 6 and may be of different widthswith the outer elements being narrower and those toward the center beingwider in order to obtain the maximum heating area within the l'mits ofthe diameter of the cylindrical head 26 and the length of the members29. So mounted, the at electrical heating elements 29 are made to spreadin the manner of a fan or the leaves of a bock. The mechanism forspreading the flat electrical heating elements 29 may be the fiatsprings 34 (Fig. 5) attached on the flat sides of the heating elements29 between successive members and parallel to the longitudinal centerline thereof so that when the elements 29 are compressed the springs areunder expanding tension. A shock absorber 29a is disposed below thebases of the nat electrical heating elements 29 and held in place by theopposed members 32 and 33, along the ends of the elements 29, andsupported at the top by the cylindrical head 26. The elements 29 areheld together by the ring 36 (Fig. 4) slidably disposed along theopposed members 32 and 33 and actuated by the rope 31, one end of whichis attached to the ring 36 and the opposite end passed through thecasina I5 to the surface.

Within the flat electrical heating elements 29 are the resistance wires33a imbedded in asbestos or mica as shown in Figure 6 and covered bysheet iron or stainless steel in a general form of a sheath. Theelectrical leads connecting the resistance wires with the distributingpaths in the cylindrical head 26 are insulated in the manner previouslydescribed under the nrst embodiment.

The operation for the rst embodiment shown in Figures l, 2 and 3 is asfollows:

One end of a rope I1 is made fast to the lifting hook or eye I6 on thetop of the cylindrical head I3 with the ring 24 at the base as shown inFigure 2. The heater I2 is then lowered through the casing I5 of the oilwell I0 into the borehole as shown in Figure I. Substantially in theborehole and under the level II of the oil, the'rope 25 is pulledupwardly to move the ring '24 above the hinged joints I4a 0f theelectrical heating elements I4. Now free to be spread, the rope I9,actuating the inverted collapsible conical mechanism formed by thespreaders 23, is pulled upwardly which spreads the electrical heatingelements I4 in the manner shown in Figure l. The elecfrfl Conductors .20and 2I are then connected to a source of electrical energy at thesurface which supplies the necessary energy for heating the electricalheating elements i4. Usually at the beginning the amount of heat isrelatively high, forl instance 20,000 B. t. nfs per hour ormore, say`50,000 B. t. nfs.'I When the oil is warmed up sufliciently', to around200 F. or even higher, `the heat input may be reduced conveniently bydecreasing the voltage ci the current passing through the resistancewires Mb. The regulation of the heat input is conveniently obtained byan electrical transformer at the surface and the temperature of both theheating elements I4 and the oil may be determined by thermocouples. Suchheating kmight last from l to 5 days or more'until a sufficientlyincreased ow of oil from the oil-bearing rock into the borehole' isassuredand is dependent upon the nature and thickness oi the wax depositand upon the rate of heating. f

After the wax in the pores of the oil-bearing rock is melted, the heateris preferably pulled out from the well, the heating elements beingfolded automatically when pulled through the casing. The heater may bereplaced now by any suitable instrument to lift the oil to the surfacefor regular exploitation.

The operation of the electrical heater shown in the second embodiment,Figures 4, 5, and 6, is substantially the same except that the ilatelectrical heating elements 29 automatically spread in the boreholewhenthe ring 3E is moved upwardly above the hinged joints as sho-vn inFigure 5 by pulling upwardly'on the rope Si.

An oil well 1,200 feet deep, was producing originally by pumping 16barrels of parafiin base crude daily. After three years the productionfell to 4 barrels per day whereupon electric heating in accordance withthis invention was applied for three days. During the day, the heat wasapplied at the rate of about 20,000 B. t. u.s per hour, the second day15,0% B. t. u.s, the third day 10,000 B. t.y ufs `On the fourth day, theelectric heater was replaced by a pump and the production rose to. 14barrels per day for o-ne week and then was stabilized for'several monthsat a level of llbarrels per day.

Of course the heating apparatus may be composed of one or a vpluralityof the electrical heaters and may be attached tothe regular instrumentsused in" lifting the oil to the surface or may be used independently.

It is apparent that the specific illustrations above shown have beengiven by way of illustration and not by way of limitation and that thestructures above described are subject to wide variation and modicationwithout departing from the scope or intent of the invention. all ofwhich variations and modiiications are to be included within the scopeofthe present invention.

What is claimed is:

l. An electrical heater adapted to raise the temperature of the oil inthe borehole of an oil well comprising at least two electrical heatingelements, means lowering the electrical heating elements into theborehole below the surface of the oil therein, means supplying anelectrical current for the electrical heating elements, and meansspreading the electrical heating elements and adapted to diffuse thehea-t throughout the oil body, in which the means spreading theelectrical heating elements are characterized by being of the umbrellatype and comprises a spreader for each of the electrical heatingelements, means hingedly connecting one end of the spreaders in opposedrelationship on the inside surface portions of the electrical heatingelements, the opposite ends of the spreaders extending downwardlybetween the electrical heating elements, means hingedly connecting thedownwardly extended ends cf the spreaders, and means applying anupwardly directed force to the downwardly extended ends of thespreaders.

' 2. An electrical heater adapted to raise the temperature of the oil inthe borehole of an oil well according to claim l in which the. meansspreading the electrical heating elements is characterized by being ofthe fan type and comprises a spring disposed between the electricalheating elements and adapted to be under tenl sion prior to thespreading of the elements.

3. An electrical heater `adapted to raise the temperature of the oil inthe borehole of an loil well according to claim 1 in 'which theelectrical heating elements are or? the umbrella type and characterizedby being substantially elongated cylindrical members.

Il. An electrical heater adapted to raise the temperature of the oil inthe borehole of an oil well according to claim l. in which theelectrical heating elements are of the fan type and characterized bybeing substantially elongated rectangular members.

5. An electrical heater of the umbrella type adapted to raise thetemperature of the oil in the borehole of an oil well comprising a headof appropriate design for lowering through the casing of the oil well,at least twc substantially cylindrical electrical heating elementshingedly disposed in opposed relationship on the base of the head,electrical resistance wires in the heating elements, means connectingthe resistance wires to an outside source of electrical energy; theelectrical heater further comprising a spreader hingedly attached toeach heating element and adapted to spread the same in the manner of anumbrella.

6. An electrical heater of the umbrella type adapted to raise thetemperature of the oil in the borehole of an oil well comprising asubstantially airtight cylindrical head, the diameter of the head beingsubstantially less than .the diameter of the oil 'well casing, anopening through the cylindrical head along the'axis thereof, a tubularmember disposed on the base of the cylindrical head and alined with theopening, a, lifting fastener disposed on the top surface portion of thecylindrical head; the electrical heater further comprising a rope, oneend of the rope being attached to the lifting fastener, the rope beingof sufficient length to permit lowering of the heater into the borehole;the electrical heater further comprising at least two substantiallycylindrical electrical heating elements, means hingedly attaching oneend of the elements to the base of the cylindrical head in opposedrelationship and with the tubular member therebetween, electricalresistance wires disposed in the cylindrical heating elements, meanselectrically connecting the resistance wires to an outside source ofelectrical energy; the electrical heater further comprising meansreleasably maintaining the electrical heating elements together, andmeans spreading said elements substantially in the manner of an umbrellacomprising at least one spring-like rod for each electrical heatingelement, means hingedly connecting one end of the rods to the heatingelements in opposed relationship and substantially along the line ofintersection of a plane tangent to the end of the tubular member withthe heating elements, the opposite ends of the rods extending downwardlybetween the heating elements and below the end of the tubular member,means hingedly connecting the downwardly extended ends of the rod; theelectrical heater further comprising a rope, one end of the rope beingpassed through the opening in the cylindrical head and tubular memberand connected to the downwardly extended and hingedly connected ends ofthe rods, the opposite end of the rope being passed through the oil wellcasing to the surface.

7.An electrical heater of the umbrella type adapted to raise thetemperature of the oil in the borehole of an oil well according to claim6 in which the means releasably maintaining the electrical heatingelements together comprises a ring slidably disposed along theelectrical heating elements, and means raising the ring substantiallyabove the hinged connections of the electrical heating elements on thebase of the cylindrical head.

8. An electrical heater of the fan type adapted to raise the temperatureof the oil in the borehole of an oil well comprising a substantiallyairtight cylindrical head, the diameter of the head being substantiallyless than the diameter of the oil well casing, a lifting fastenerdisposed n the top surface portion of the head, and a rope, meanssecuring one end of the rope tc the lifting fas*- ener, the rope beingof sufficient length to permit lowering of the heater into the boreholefrom the surface; the electrical heater urther comprising at least twoat electrical heating elements hav-- ing a width substantially less thanthe diameter 1,

of the head, means hingedly attaching one end of the at electricalheating elements on the base of the head in opposed relationship,electrical resistance wires disposed in the fiat electrical heatingelements, means insulating the wires, and means connecting theresistance wires to an outside source of electrical energy and adaptedto raise the temperature of the fiat electrical heating elements; theheater further comprising means spreading the fiat electrical heatingelements, and means releasably maintaining the at electrical heatingelements together.

9. An electrical heater of the fan type adapted to raise the temperatureof the oil in the borehole of an oil well according to claim 8 in whichthe means spreading the flat electrical heating elements comprises aspring member disposed between opposed surface portions of each flatelectrical heating element and adapted to be under tension prior to thespreading of said members.

10. An electrical heater of the fan type adapted to raise thetemperature of the oil in the borehole of an oil well according to claim8 in which the means releasably maintaining the fiat electrical heatingelements together comprises a ring slidably disposed therealong andmeans moving the ring above the hinged mounting means of the flatelectrical heating elements on the base of the head.

'11. An electrical heater of the fan type adapted to raise thetemperature of the oil in the borehole of an oil well comprising asubstantially airtight cylindrical head, the diameter of the head beingsubstantially less than the diameter of the oil well casing, a liftingfastener disposed on the top surface portion of the head, and a rope,means securing one end of the rope to the lifting fastener, the ropebeing of sufficient length to permit lowering the heater into theborehole from the surface; the electrical heater further comprising aplurality of substantially elongated at electrical heating elementsofprogressively decreasing width, the maximum width being substantiallyless than the diameter of the head, means hingedly connecting the fiatelectrical heating elements to the base of the head on either side ofthe center in opposed relationship and with the flat electrical heatingelements of greatest width on the inside with those of progressivelynarrower widths in consecutive order toward the circumference of thehead, a spring disposed'between each consecutive flat electrical heatingelement and adapted to be under tension when the planes of the atelectrical heating elements are parallel to the plane through the axisof the head; the heater further comprising a shock absorber disposedbelow the base of the hat electrical heating elements, opposed membersdisposed on the cylindrical head along the ends of the fiat electricalheating elements and adapted to support the shock absorber; the heaterfurther comprising electrical resistance wires disposed in the flatelectrical heating elements, means insulating the wires, and meansconnecting the electrical resistance wires in parallel through thecylindrical head to an outside source of electrical energy and adaptedto raise the temperature of the at electrical heating elements; theheater further comprising means releasably maintaining the at electricalheating elements together comprising a ring slidably disposed along theopposed members of the shock absorber, and means raising the ring abovethe hinged means of the fiat electrical heating elements on the head.

JAKUB SCHMER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 780,279 Gardner a- Jan. 17, 19051,450,658 Warnick Apr. 3, 1923

